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CSCI 6962: Server-side Design and Programming

CSCI 6962: Server-side Design and Programming. Java Server Faces Components and Tags. JSF Tags. JSF pages contain mix of HTML and JSF tags <h:____ html tags (most correspond to standard html) <f:____ facelet tags (specific to JSF capabilites )

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CSCI 6962: Server-side Design and Programming

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  1. CSCI 6962: Server-side Design and Programming Java Server Faces Components and Tags

  2. JSF Tags • JSF pages contain mix of HTML and JSF tags • <h:____htmltags (most correspond to standard html) • <f:____facelettags (specific to JSF capabilites) • <c:____JSTLtags (simple control flow actions) • XML format • Defined in libraries loaded in xhtml tag at beginning

  3. JSF Tags • JSF pages mapped to servlet • Code in web.xml generated when JSF webapp created • Converted to servlet and run on demand (like JSP)

  4. Example JSF configure.xhtml order.xhtml ComputerBean

  5. Checkbox • Tag: <h:selectBooleanCheckbox value=“#{beanname.variable}”/> • Maps to a boolean member variable in bean • Can access as boolean in bean methods Can set initial state of checkbox (true if checked)

  6. Checkbox Mehtods • Requires methods • public void setVariable(booleanvalue) • public booleanisVariable()

  7. Conditional Output • Goal: Display whether monitor selected • Methods: • Place condition in JSF page to only display row if monitor checked • Place condition in bean to create an output string in html (either a table row or nothing) and display it in JSF page

  8. JSF Page Condition • Requires use of tags in JSTL library • Cannot just put executable code in page as in JSP • <c:if test=“boolean value”> html</c:if> • Condition can be bean value If true Display this

  9. Bean Value Condition • Create “get” method for string to display • Multiple possible strings based on bean values • Create outputText to display that string • escape=“false” causes html to be rendered (instead of ‘<‘ and ‘>’) • Possible security hole (cross site scripting)

  10. List-like Form Elements • Basic syntax like select/option lists in html • Grouped into single select and multiple select types • Contains list of selectItem elements:<f:selectItemitemLabel=“label” itemValue=“value”/> <h:selectOneListbox <h:selectOneMenu <h:selectOneRadio <h:selectManyCheckbox <h:selectManyListbox <h:selectManyMenu label to display value to pass

  11. Radio Buttons • Example: Radio button for memory choices • Linked to Stringvariable in bean

  12. Radio Buttons • Evaluates to a single String value • Can manipulate in bean • Can access in JSF page

  13. Multiple Selection Elements • Must be linked to array in bean

  14. Multiple Selection Elements • Can manipulate like array • Iterate through elements, search, etc. • Note that array does not evaluate to null if nothing chosen • Can check whether length property = 0 to check whether user selected anything

  15. Iteration JSTL Tag • Can use like simple for loop<c:forEachvar=“loopiterator” begin=“inital” end=“final” step=“step”/>html</c:forEach> • Similiar tofor (intloopiterator = initial;loopiterator<= final;loopiterator+= step) {…

  16. Iteration JSTL Tag • More useful for looping through collection • Arrays, database tables, etc. • <c:forEachitems=“array or collection”var=“ith value” />html that uses var</c:forEach> • Example: Array stooges = [“Larry”, “Curley”, “Moe”]<c forEach items=“stooges” var=“stooge”/> • Loops 3 times • Iteration 1: stooge = “Larry” • Iteration 2: stooge = “Curley” • Iteration 3: stooge = “Moe”

  17. Iteration JSTL Tag • Example: Displaying all software selected by user • In software array in bean ith element of software array Display that value in outputLabel

  18. Defining List Elements in Bean • List contents hardwired in JSF page • Difficult to modify in future • List contents may be defined by business model • Better if list elements defined in bean instead of JSF • JSF links to bean to get list elements

  19. Bean Generated Lists • Construct array of SelectItem objects in bean • Must import javax.faces.model.* in bean • Provide get method to return the array • Use <f:selectItems value=“bean.arrayName”/>to insert allSelectItem objects in array into list

  20. Array of SelectItems • Syntax:private static SelectItem[] arrayName { new SelectItem(“value1”, “label1”), new SelectItem(“value2”, “label2”), new SelectItem(“value3”, “label3”), …}; public getArrayName() { return arrayName;} Construct new SelectItem for each element in list

  21. Bean Generated Lists

  22. Bean Generated Lists

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